package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.RandomUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.cache.annotation.CacheConfig;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;
    @Override
    public Result queryById(Long id) {
        //缓存穿透
        Shop shop = cacheClient.queryWithPassThrough(RedisConstants.CACHE_SHOP_KEY,id,Shop.class,this::getById,RedisConstants.CACHE_SHOP_TTL,TimeUnit.MINUTES);
        //互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);
        //逻辑过期解决缓存击穿
        //Shop shop = cacheClient.queryWithLogicalExpire(RedisConstants.CACHE_SHOP_KEY,id,Shop.class,this::getById,RedisConstants.CACHE_SHOP_TTL,TimeUnit.MINUTES);

        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        return Result.ok(shop);
    }

    public Shop queryWithPassThrough(Long id){
        String key= RedisConstants.CACHE_SHOP_KEY +id;
        //从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //存在，返回
        if(StrUtil.isNotBlank(shopJson)){

            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否为空值
        if(shopJson!=null){
            return null;
        }

        //不存在，根据id查询数据库
        Shop shop = getById(id);
        //数据库不存在，返回错误
        if(shop==null){
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key,"",RedisConstants.CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }

        //存在，写入redis，再返回
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop),RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        return shop;
    }
    public Shop queryWithMutex(Long id){
        String key= RedisConstants.CACHE_SHOP_KEY +id;
        //从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //存在，返回
        if(StrUtil.isNotBlank(shopJson)){

            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否为空值
        if(shopJson!=null){
            return null;
        }
        //开始实现缓存重建
        //获取互斥锁
        String lockKey=RedisConstants.LOCK_SHOP_KEY+id;
        Shop shop = null;
        try {
            boolean islock = tryLock(lockKey);
            //判断是否获取成功

            //失败，则休眠并重试
            if(!islock){
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //成功，则进行下面代码

            //不存在，根据id查询数据库
            shop = getById(id);
            // 模拟重建的延时
            Thread.sleep(200);
            //数据库不存在，返回错误
            if(shop==null){
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key,"",RedisConstants.CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }

            //存在，写入redis，再返回
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop),RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
        finally {
            //释放互斥锁
            unlock(lockKey);
        }

        return shop;
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if(id==null){
            return Result.fail("店铺id不能为空");
        }
        //更新数据库
        updateById(shop);
        //删除缓存
        stringRedisTemplate.delete(RedisConstants.CACHE_SHOP_KEY+id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //判断是否需要根据坐标查询
        if(x== null||y==null){
            //不需要坐标查询，按照数据库查询
            // 根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        //计算分页参数
        int from=(current-1)*SystemConstants.DEFAULT_PAGE_SIZE;
        int end=current*SystemConstants.DEFAULT_PAGE_SIZE;

        //查询redis，按照距离排序，分页 结果:shopId distance
        String key=RedisConstants.SHOP_GEO_KEY+typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(key, GeoReference.fromCoordinate(x, y), new Distance(5000), RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end));

        //解析出id
        if(results==null){
            return Result.ok();
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if(list.size()<=from){
            return Result.ok(Collections.emptyList());
        }
        //截取从from到end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String,Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result->{
            //获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //获取距离
            Distance distance = result.getDistance();

            distanceMap.put(shopIdStr,distance);
        });
        //根据id查询店铺
        String idStr = StrUtil.join(",",ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for(Shop shop:shops){
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        //返回
        return Result.ok(shops);
    }

    public void saveShopToRedis(Long id,Long expireSeconds)throws InterruptedException{
        //查询店铺数据
        Shop shop=getById(id);
        Thread.sleep(200);
        //封装逻辑过期时间
        RedisData redisData=new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //写入Redis
        stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
    }
    /**
     *尝试获取锁
     * @param key
     * @return
     */
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", RedisConstants.LOCK_SHOP_TTL, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    /**
     * 释放锁
     * @param key
     */
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }
}
